Exhaust gas treatment devices are customarily used to remove pollutants, such as hydrocarbons (HC) and nitrogen oxides (NOx), from the exhaust gas of internal combustion engines. However, these exhaust gas treatment devices have to reach a certain operating temperature before they become active. Therefore, for a certain period of time after the cold start of an engine, pollutants are discharged to the atmosphere to an unabated extent, which makes a considerable contribution to the overall quantity of pollutants emitted during a journey.
To minimize exhaust emissions during a cold start, it is desirable to shorten the time required to reach the operating temperature of the exhaust gas treatment device. To do this, the load on the internal combustion engine is often artificially increased to generate a considerable flow of exhaust gas at relatively high temperature. However, the higher load on the internal combustion engine at the same time leads to an increased production of pollutants, which runs contrary to the desired reduction in emissions.